Gyratory crushers are used for crushing ore, mineral and rock material to smaller sizes. Referring to FIG. 1, a typical crusher comprises a frame 100 having an upper frame 101 and a lower frame 102. A crushing head 103 is mounted upon an elongate shaft 107. A first crushing shell 105 is fixably mounted on crushing head 103 and a second crushing shell 106 is fixably mounted at top frame 101. A crushing zone 104 is formed between the opposed crushing shells 105, 106. A discharge zone 109 is positioned immediately below crushing zone 104 and is defined, in part, by lower frame 102.
Upper frame 101 may be further divided into a topshell 111, mounted upon lower frame 102 (alternatively termed a bottom shell), and a spider 114 that extends from topshell 111 and represents an upper portion of the crusher. Spider 114 comprises two diametrically opposed arms 110 that extend radially outward from a central cap 112 positioned on a longitudinal axis 115 extending through frame 100 and the gyratory crusher generally. Arms 110 are attached to an upper region of topshell 111 via an intermediate annular flange 113 that is centred around longitudinal axis 115. Typically, arms 110 and topshell 111 form a unitary structure and are formed integrally.
A drive (not shown) is coupled to main shaft 107 via a drive shaft 108 and suitable gearing 116 so as to rotate shaft 107 eccentrically about longitudinal axis 115 and to cause crushing head 103 to perform a gyratory pendulum movement and crush material introduced into crushing gap 104.
Example gyratory crushers having the aforementioned topshell and spider assembly are described in U.S. Pat. No. 2,832,547; US 2002/017994; WO 2004/110626 and US 2011/0192927.
In order to maximise the opening into the crushing zone, it is conventional for the spider arms 110 to extend from the annular flange 113 at the flange outermost perimeter. As the flange 113 extends radially outward beyond the circumferential wall of the topshell 111, reinforcements are typically required on the external facing surface of the topshell walls being positioned directly below the spider arms 111.
These reinforcing ribs that act to transmit the axial forces imparted onto the topshell 111 from spider 110 are necessary due to the non-optimised alignment of the spider arms 111 and the circumferential wall of the topshell. These ribs are disadvantageous as they both add additional weight to the crusher and increase complexity of manufacturing.
Accordingly, what is required is a gyratory crusher frame that addresses the above problem.